What do I need for this?

[CookieTheMonsta]

I need help with WiFi. So router and phone is at my sisters room, and of course signal of that router is too low to get to my room. It gets to it, but I can't load anything because signal is way too low. Now I'm confused what I need. I want to have router kind of device in my room, so I can emit signal. Problem also, is that I have LAN cable coming to my room, but I would like to still connect my PC via LAN cable and have that device that emits signal so that I can connect my Android phone to it. Can somebody tell what I need!? I thought of buying new router with better antenna but if there's a way to just buy new device that I can put in my room so I have best signal possible that would be really nice. And can somebody tell me the difference between switch, access point and repeaters (I know there is internet but could somebody explain it better) ? Thanks

[SubTract]

If you have an ethernet port coming into your room, just buy a wireless router without the dsl or cable part. 

Plug your ethernet cable into the internet port set up the wifi for your phone, then simply use ethernet from the router to your desktop.

Being that its only serving internet to your phone wirelessly make sure it has good ethernet and don't stress to much about the wifi aslong as it has it.

[CookieTheMonsta]

So you want to say that I should buy wireless router, plug Ethernet cable into it, enable WiFi on it, and run Ethernet cable from it to my pc? And that won't interfere with my 1st router?

[SubTract]

that's the general idea yeah.

It will have a unique SSID (Name) and password (Well this can be the same if you really want)

So you will connect to it as if its an entirely different network.